Differential Impact of an Eclipse on Photosynthetic Performance of Trees with Different Degrees of Shade Tolerance

Abstract

Solar eclipses represent a natural and unexpected event for plants that can potentially affect photosynthetic performance at the individual level. This effect, however, has seldom been evaluated. Here, we measured the impact of a total solar eclipse on the photosynthetic rate of different tree species—located in the Bosque Fray Jorge National Park, Chile—with varying degrees of shade tolerance. Specifically, we assessed whether the rapid and progressive light limitation facilitated by a solar eclipse would negatively impact the photosynthetic responses of these tree species and whether their photosynthetic performance would have a greater decrease when the percentage of eclipse shadow was higher, particularly in the less shade-tolerant species. To accomplish this, we compared daily changes in the photosynthetic rates of three tree species during a control (non-eclipse) vs. an eclipse day that occurred on 2 July 2019. Overall, tree species showed differences between a non-eclipse and eclipse day in the daily dynamics of their photosynthetic performance, with this trend being most evident at the peak of the solar eclipse. Additionally, each species showed a different pattern of de-epoxidation in accordance with its degree of shade tolerance. Our results suggest that solar eclipses negatively affect the photosynthesis of the studied Chilean tree species, which may be related to energy dissipation capacity via the de-epoxidation of xanthophyll pigments. This effect was more evident in shade-intolerant species, indicating that eclipses can present different consequences for the overall performance of various plant species.

Bioelectrical Synchronisation of Spruce Trees during a Solar Eclipse

“…Heightened tendencies of individuals to form collectives by huddling, gathering and synchronising group movements during solar eclipses are also seen across several animal groups, terrestrial and aquatic alike (7). If solar eclipses play such a vital role in shaping individuals and their groups to ensure collective survival across species, it is remarkable that very little is known about how plants respond to these astronomical events and such knowledge is limited to responses at the individual level (8)(9)(10)(11)(12)(13)(14) overlooking that group behaviour has also been observed in plants (15,16). Here, we use a remote measurement system we have developed to simultaneously monitor multiple trees in a forest (17) to directly test whether individual trees respond to a solar eclipse together as a larger living collective, the forest.…”